Study of the Reactions n[over ¯]p→2π^{+}π^{-}, 2π^{+}π^{-}π^{0}, and 2π^{+}π^{-}2π^{0} Using J/ψ→pπ^{-}n[over ¯]

Area of Science:

• Particle Physics
• Antimatter Interactions
• Hadron Spectroscopy

Background:

• Antineutron-nucleon interactions are crucial for understanding the strong nuclear force.
• Experimental data for antineutron interactions, especially at higher momenta, are scarce.
• Previous studies were limited to lower antineutron momenta.

Purpose of the Study:

• To experimentally investigate antineutron-proton interactions.
• To study the reactions antineutron-proton to 2π⁺π⁻, 2π⁺π⁻π⁰, and 2π⁺π⁻2π⁰.
• To provide the first experimental data for antineutron momenta exceeding 800 MeV/c.

Main Methods:

• Utilized J/ψ events collected by the BESIII detector at the BEPCII storage ring.
• Produced antineutrons via the J/ψ → pπ⁻n̄ decay.
• Used protons from hydrogen nuclei in the beam pipe cooling oil as targets.

Main Results:

• Collected (10.087±0.044)×10⁹ J/ψ events for analysis.
• Studied antineutron momenta ranging from 200 to 1174 MeV/c.
• Pioneered a novel method for studying antineutron-nucleon interactions at an e⁺e⁻ collider.

Conclusions:

• This work provides the first experimental data for antineutron-nucleon interactions at momenta above 800 MeV/c.
• The novel experimental approach opens new avenues for antimatter research at colliders.
• The results contribute significantly to the understanding of fundamental particle interactions.